With an old non-AS trialer I used to have I used one of those clear plastic RV Hyrdo-flush fittings that allowed me to backflush the waste tank. I can't get it to fit on my '94 LY as the waste valve is set back and is set to drain via a hole in the floor of the storage compartment which houses it all. I had purchased a portable FloJet mascerator pump, but it looks like I'm going to have to modify the waste fillings to get it to fit.
For chemicals, I have been using Pinesol (the original liquid cleaner) since the mid-1980's. While in motion, it washes the tank, there is a bit of oil in it which lubricates the valves and it has a pine smell to it which is not unpleasant. It's also easy to find and much less expensive than some of the packet cleaners.
I've got to admit that I squirmed in my seat when I watched the antics of Robin Williams in "RV", especially when he was connecting up the waste hoses.
1987 Excella 32-foot
1999 Dodge Ram 2500HD Diesel